Device for detecting fuel in oil by gas-phase analysis

Abstract

Turbine engine comprising a lubrication circuit (20) through which a lubricant (21) passes, and a supply circuit through which a fuel (41) passes, wherein the lubrication circuit (20) comprises a chamber (22) in which a liquid phase (23) and a gas phase (24) arise, the lubrication circuit (20) further comprising a sensor (30) arranged to detect the presence of fuel vapour (41) in the gas phase (24). Also disclosed are an aircraft provided with such a turbine engine, and a leak detection method.

Description

[0001] DESCRIPTION

[0002] TITLE OF THE INVENTION

[0003] DEVICE FOR DETECTING FUEL IN OIL BY GAS PHASE ANALYSIS

[0004] TECHNICAL FIELD

[0005] The invention relates to the field of engine lubrication circuits and more particularly to the prevention of pollution of such circuits.

[0006] STATE OF THE PRIOR ART

[0007] In aircraft, the lubrication system is essential to ensure the proper functioning of engines. However, the lubrication system can become contaminated with fuel, which can cause engine performance and flight safety issues, particularly due to the risk of ignition. Fuel detection in the lubrication system is therefore crucial to ensure aircraft reliability and safety.

[0008] Heat exchangers are used to transfer heat generated by engines from the lubrication system to the fuel system to preheat the fuel before it is injected into the engines. These heat exchangers between the lubrication system and the fuel system can leak, which can cause fuel to contaminate the lubrication system.

[0009] There are several fuel detection technologies in the aircraft lubrication system, such as infrared absorption spectroscopy, Raman spectroscopy, and electrical impedance analysis. These technologies are designed to detect the presence of fuel in different parts of the lubrication system, including filters, heat exchangers, and lines. Fuel detection systems must be robust and reliable to operate under varying environmental conditions, such as high temperatures and pressures, as well as in environments with vibration and shock. Because fuels and lubricants have similar chemical properties, it is difficult to clearly establish the presence of fuel in the oil at low concentrations of fuel in the lubricant.Given the impact of fuel in oil, even at very low concentrations, a reliable and sensitive device is required.

[0010] SUBJECT OF THE INVENTION

[0011] The invention aims to improve the sensitivity of fuel detection in a lubricant circuit.

[0012] STATEMENT OF THE INVENTION

[0013] For this purpose, a turbomachine is provided comprising a lubrication circuit traversed by a lubricant and a supply circuit traversed by a fuel, the lubrication circuit comprising an enclosure in which a liquid phase and a gaseous phase are established, the lubrication circuit also comprising a sensor arranged to detect the presence of fuel vapor in the column.

[0014] We then obtain a turbomachine equipped with a reliable and robust measuring device which analyses a particular parameter (gas phase) which is naturally denser in information and whose analysis is easier and can be carried out using robust and reliable sensors.

[0015] According to other particular, non-exclusive and optional embodiments of the invention: a fluid connection between the sensor and the enclosure comprises an anti-splash device.

[0016] - the anti-splash device comprises a column and / or a grid and / or a membrane; the sensor is a platinum wire catalytic sensor; the enclosure is an oil reservoir; the sensor is fluidically connected to the enclosure by an oiled air pipe; the turbomachine comprises a gas phase generation device; the gas phase generation device comprises a heating device.

[0017] The invention also relates to an aircraft comprising a turbomachine as described above as well as a method for detecting a leak from a supply circuit traversed by a fuel to a lubrication circuit traversed by a lubricant in such a turbomachine, the method comprising the following steps: taking a portion of the gaseous phase from the enclosure; detecting the presence of fuel vapor in the gaseous phase; issuing an alert when the gaseous phase contains a quantity of fuel vapor greater than a predetermined threshold.

[0018] Advantageously, the method comprises an additional step of generating the gas phase, preferably by heating.

[0019] Other characteristics and advantages of the invention will appear on reading the following description of a particular non-limiting embodiment of the invention.

[0020] BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Reference will be made to the attached figures, including:

[0022] [Fig. 1] Figure 1 is a schematic sectional representation of a turbomachine;

[0023] [Fig. 2] Figure 2 is a partial schematic plan view of a fuel circuit and a carburetion circuit according to the invention;

[0024] [Fig. 3] Figure 3 is a schematic representation of the sensor of Figure 2. DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS

[0025] In a turbomachine, here a turbojet marked 1 in Figure 1, the air is admitted into an inlet sleeve 2 to pass through a fan comprising a series of rotating blades 3 before splitting into a central primary flow which circulates in a vein called a circulation vein of a primary air flow and a secondary flow surrounding the primary flow. The primary flow is compressed by compressor stages 4 and 5 before reaching a combustion chamber 6, after which it expands by passing through turbines 7, before being evacuated while generating thrust. The secondary flow is propelled directly by the fan to generate the main thrust.

[0026] The compressor stages 4 and 5 comprise fixed distributors regularly spaced around a shaft 8 mounted for rotation around a longitudinal axis AX in a nacelle 9 surrounding the assembly. The blades of the compressor stages 4 and 5 and of the turbines 7 are integral in rotation with the shaft 8. The shaft 8 is mounted for rotation relative to the nacelle 9 using several oil-lubricated bearings 10 which are confined in enclosures 11.

[0027] In this text, the terms "inner" or "internal" and "outer" or "external" are used with reference to the position or orientation relative to the axis of rotation of the turbine of the turbojet engine 1. In this text, the terms "upstream" and "downstream" are used with reference to the position or orientation of an element according to the direction of air flow in the turbojet engine 1. An axial direction, a radial direction which is orthogonal to the axial direction and a circumferential direction which is orthogonal to the axial and radial directions are also defined.

[0028] The turbojet 1 comprises a lubrication circuit 20 traversed by a lubricant 21 and a supply circuit 40 traversed by a fuel 41. The lubrication circuit 20 comprises an enclosure 22 - here a tank - in which a liquid phase 23 and a gaseous phase 24 of the lubricant 21 are established. The lubrication circuit 20 comprises a pump 25 and is connected to a heat exchanger 50 to constitute the hot circuit. The supply circuit 40 is also connected to the exchanger 50 to constitute the cold circuit. The calories from the lubrication circuit 20 are thus transferred to the supply circuit 40. An oiled air pipe 26 is connected to the enclosure 22. A column T1 is connected to the pipe 26 by its first end 28 to be fluidically connected to the enclosure 22 so as to be traversed by the gaseous phase 24. The second end 29 of the column T1 is provided with a sensor 30 of the catalytic type with platinum wire.The end 28 is equipped with an anti-splash device, here a membrane 31.

[0029] An electric heater 60 extends against a wall - here a bottom 22.1 - of the enclosure 22. A suction device, such as a vacuum pump or jet pump, can also be used to create the vapor phase. It is sufficient to place it at the top of the oiled air pipe 26. An anti-splash device such as that at the end 28 can then be added between the enclosure 22 and the pipe 26, in order to guarantee the presence of only vapor in the pipe 26 and in the suction device at its top.

[0030] The pump 25, the sensor 30 and the electric heater 60 are connected to a control and command unit 70.

[0031] The sensor 30 and its operation will be described in more detail with reference to Figure 3. The sensor 30 comprises a platinum wire 32 which describes a first set of turns 33 and a second set of turns 34. The first set 33 is covered with a catalyst 35 to constitute a catalytic wire measurement resistive circuit and the second set 34 is covered with a deactivator 36 to constitute a reference resistive circuit. The sets 33 and 34 are respectively protected by a ceramic coating 33.1 and 34.1 and have a common terminal 37. The first set 33 comprises a free measurement terminal 38 and the second set 34 comprises a free reference terminal 39.

[0032] The sensor 30 operates by measuring the electrical conductivity of the platinum wire 32.

[0033] The catalyst 35 of the platinum wire 32 allows the fuel vapor molecules to react with the oxygen naturally present in the air. This reaction modifies the physical properties of the platinum wire and in particular its electrical conductivity and therefore the voltage between terminals 37 and 38. The voltage measured between terminals 37 and 39 of the reference electrode provides a stable reference for measuring the electrical conductivity of the catalytic platinum wire and thus cancels out the effects of environmental parameters that may affect the measurement between terminals 37 and 38, such as, for example, ambient temperature and ambient pressure.

[0034] When fuel vapor molecules 41 are present in the gas phase 24, they react with the catalyst 35 on the wire 32, changing its electrical conductivity. This change in resistance is measured and is proportional to the concentration of fuel vapor in the gas phase 24.

[0035] In operation, the device of the invention follows the following steps. According to a first step, the unit 70 controls the start-up of the heater 60 in order to generate the gaseous phase 24. According to a second step, the column T1 takes a portion of the gaseous phase 24 from the enclosure 22 and brings it to the sensor 30. According to a third step, the unit 70 measures the current between the terminals 37 and 38 and performs a measurement compensation using a measurement carried out between the terminals 37 and 39. The unit 70 interprets the results obtained and detects or not the presence of fuel vapor 41 in the gaseous phase 24. According to a last step, the unit 70 issues an alert when the gaseous phase 24 contains a quantity of fuel vapor 41 greater than a predetermined threshold.

[0036] Of course, the invention is not limited to the embodiment described but encompasses any variant falling within the scope of the invention as defined by the claims.

[0037] In particular, although here the sensor is located at the end of the column, the invention also applies to a device without a column in which the sensor would be located on a wall of the oiled air pipe or directly in the enclosure; although here the column is connected to the pipe, the invention also applies to other methods of connection between the column and the enclosure, such as for example a branch tee;

[0038] -although here the sensor is a platinum wire catalytic sensor, the invention also applies to other types of sensors arranged to detect the presence of fuel vapor in the column, such as for example an infrared sensor or a Davy type sensor or an electrochemical detector; although here the anti-splash device comprises a membrane, the invention also applies to other types of anti-splash device such as for example a grid or a baffle; although here a heater is used to generate the gas phase, the invention also applies to a measuring device without heater, the gas phase being generated by natural evaporation.

Claims

CLAIMS 1. Turbomachine (1) comprising a lubrication circuit (20) traversed by a lubricant (21) and a supply circuit (40) traversed by a fuel 41, the lubrication circuit (20) comprising an enclosure (22) in which a liquid phase (23) and a gaseous phase (24) are established, the lubrication circuit (20) also comprising a sensor (30) arranged to detect the presence of fuel vapor (41) in the gaseous phase (24) in which a fluid connection between the sensor (30) and the enclosure (22) comprises an anti-splash device (31).

2. Turbomachine (1) according to claim 1, in which the anti-splash device (31) comprises a column (27) and / or a grid and / or a membrane (31).

3. Turbomachine (1) according to any one of the preceding claims, in which the sensor (30) is a platinum wire catalytic sensor (32).

4. Turbomachine (1) according to any one of the preceding claims, in which the enclosure (22) is an oil reservoir.

5. Turbomachine (1) according to any one of the preceding claims, in which the sensor (30) is fluidically connected to the enclosure by an oiled air pipe (26).

6. Turbomachine according to any one of the preceding claims, comprising a device (60) for generating the gas phase (24).

7. Turbomachine (1) according to claim 6, in which the device for generating the gas phase comprises a heating device (60).

8. Aircraft comprising a turbomachine (1) according to any one of the preceding claims.

9. Method for detecting a leak from a supply circuit (40) through which a fuel (41) flows to a lubrication circuit (20) through which a lubricant (21) flows in a turbomachine (1) according to any one of claims 1 to 8, comprising the following steps: taking a portion of the gaseous phase (24) from the enclosure (22); detecting the presence of fuel vapor (41) in the gaseous phase (24); issuing an alert when the gaseous phase (24) contains a quantity of fuel vapor (41) greater than a predetermined threshold.

10. Leak detection method according to claim 9, comprising an additional step of generating the gas phase (24), preferably by heating.

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